1. Field of the Invention
The present invention relates generally to imaging devices. The invention also relates to methods of packaging such devices. More particularly, the invention relates to a transparent plastic package for supporting and/or protecting a photosensitive semiconductor device.
2. Discussion of the Related Art
Solid-state imaging devices are known in the art. They are used to generate electrical signals representative of an incident image. The devices may be responsive to visible, ultraviolet and/or infrared radiation. The devices may also be used to generate color component signals. Solid-state imaging devices are described in U.S. Pat. No. 5,708,263 (Wong), U.S. Pat. No. 5,461,425 (Fowler et al.) and U.S. Pat. No. 4,441,125 (Parkinson).
Prior art imaging devices are packaged in ceramic and glass plate structures. Such packages are generally cumbersome and inconvenient, and the materials are relatively expensive. In addition, the known packages require complicated methods of assembly. A ceramic housing must first be produced. The ceramic housing is used to provide support for the glass plate. The housing must be carefully constructed to ensure proper alignment of the imaging device and the glass plate. Then, the imaging device is secured within the ceramic housing. The imaging device needs to be properly aligned in the housing to avoid misalignment with the plate, which could cause optical distortion. And before the glass plate is applied, steps must be taken to provide electrical communication from the leads of the imaging device to the exterior of the solid ceramic housing.
Then, the glass plate is applied and it is necessary to permanently secure the plate to the housing. The connection between the glass plate and the housing must be permanent and air tight. In addition, there should be no misalignment of or damage to the plate. All of these steps must be done in a contaminant-free environment. Dust or other contaminants on the imaging device or inside the glass plate could degrade the performance of the device. The various steps may require different machinery. Consequently, it may be necessary to move partially assembled parts from one machine to another.
There is a need in the art for imaging devices that are constructed of low-cost materials. There is also a need in the art for an uncomplicated method of packaging imaging devices. There is also a need in the art for a packaging system that is readily adaptable to existing machinery and skills in the semiconductor device manufacturing industry.